Prevention of overheating of irons and other electrically-heated appliances



May 27 1924.

1,495,814 c. A. SIMPSON PREVENTION OF OVERHEATING OF IRON 3 AND OTHER ELECTRICALLY HEATED APPLIANCES Filed March 3. 1923 INVENTO f: M 4. JW

Patented May 27, 1924.

UNITED STATES 1,495,814 PATENT OFFICE.

CHARLES ADAMS SIMPSON, OF CHRISTCHURCH, NEW ZEALAND.

Application filed March 3, 1923. Serial No. 622,511.

To all whom it may concern.

Be it known that I, CHARLEs ADAMS SIMP- soN, a British subject. a resident of 241 Lincoln Road, Christchurch, in the Dominion of New Zealand, have invented a new and useful Improvement Relating to the Prevention of Overheating of Irons and Other Electrically-Heated Appliances, of which the following is a specification.

This invention relates to electric irons and other electrically heated appliances and refers more particularly to means whereby the circuit supplying current to the heating elements of such appliances may be automatically opened upon the temperature of such appliances rising to a predetermined degree, the object of the present invention being to provide novel and effective means for this purpose, the said means being such that in addition to their embodiment in new constructions, they may be simply and conveniently applied to the conversion of existing appliances.

In carrying the invention into effect the means employed comprise a magnetic cutout adapted to operate automatically to open the controlled circuit when the current therein exceeds a predetermined limit, the special feature of this device residing in manually operable means for closing or replacing the switch of the cut-out such means being so contrived that when operating the switch they will serve also to break the circuit, in other words the said circuit will be incomplete when the said means occupy that position in which they are operative to close the switch of the cut-out, thus precluding the use of such manual means for the purpose of maintaining the circuit closed when the current therein is such as to cause the cut-out to operate in the proper manner.

The invention includes also contacts thermostatically controlled by the temperature of the heating appliance and adapted upon the temperature of the latter rising to a predetermined degree, to short-circuit the heating element of such appliance. The resistance of the circuit being reduced in this manner, the current flowing therein will correspondingly increase thereby causing the cut-out to operate and open such circuit.

In order that the nature of the invention may be clearly understood, it will now be particularly described with reference to the accompanying drawings, in which Fig. 1. shows the exterior of a cut-out constructed in accordance with the present invention.

Fig. 2. shows the interior of the same.

Fig. 3. is a sectional elevation of the same along the line AB Fig. 2.

Fig. 4. is a plan view of the rear portion of an iron equipped in accordance with the invention, and

Fig. 5. is a diagram of the wiring employed in connection with the invention.

As here shown, 1 is an iron or other elec trical heating appliance, which for simplicity will be hereinafter referred to in this description as the iron and 2 are the circuit wires or conductors whereby current from a suitable source is supplied to the heating element 3 of the iron.

Inserted in series in the said circuit 2 is a switch of any suitable form such as that here shown consisting of a blade 4 adapted to close with a contact 5 for the purpose of completing the said circuit.

The said blade 4 is adapted to be turned to disconnect with the contact 5 by means of a magnetically operable device having its winding included in series in the said circuit and which device isadapted when energized to the required extent to operate the said switch either directly or through suitable intermediate fmechanism.

In the preferred form of the construction this magnetic device consists of a solenoid coil 6 arranged with-its axis vertical and beneath the blade 4, such coil being provided with the usual iron core 7, having at its upper end a rod or extension 8 of non-magnetic material. The core 7 normally occupies its lower position within the coil as here shown but upon such coil becoming energized to the required extent the said core will be drawn upwardthereby causing its extension 8 to strike and open the switch. The said coil which may consist of one or more layers of winding is preferably encased in iron, as here shown, in order to increase its effective action upon the core.

In the preferred form of the construction provision is made for adjusting the normal position of the core in order that by raising or lowering such position the device may,

within limits, be set to operate at any de sired current. This means of adjustment may conveniently take the form here shown and consisting of a set-screw 9 tapped through aplate or other fixture at the lower .end ofithe ,coilfsothat the "point of such screw will serve as a rest for the core 7.

According to the present invention ior the purpose of closingth e blade i with its contact 5 there is provided a manually operable device adapted when closing the saidSWitch to also break the circuit in which such switch is contained. 7 i i i i c In the preferred form of the construction as here shown this deviceitakes the form of a lniob or handle l0 whichis keyed upon a spindle ll and to which latter is keyed also an armor crank 12 which" normally occupies the upward position here shown in full lines but is capable of being turned by meansof the knob 10 into the dotted line position for the purpose of closing the switch; Pivoted upon the spindlel'l is a second arm 13 whichis connected withthe said arm 12 by means of aspring 14, the

arrangement being such that while the arm is' in its normal or inoperative position the spring 14will cause the arm to bear against apin or contact 15 so as to make electrical c onnecti ontherewith; but as the arm I2'is turned into its operative position the spring willthereby be carried into such position as'to cause it to eXerciseits control of the arm 13 upon the other or opposite side of the pivotal point oi the latter with theresult that such arm 13 will instantly leave the "contactflii andturuin a downward direction until arrested by a limiting' stop 16; "If so desiredthe arm 13' may take the form of a switch-blade and the contact 15may be a spring-contact similar to the contact 5 toreceive such blade. A suitable spring 17 is preferably provided to restore the arm 12 and its knob 10 to their said normal positions after each manipulation. I V p j V The said arm '13 and contact 15' are in seffted in series in the circuit 2 that is to saya break is formed 1n such circuitaml the wire at one side of such break is con nected to the arm 13in any suitable manner as by connectlng ltfto a metallic'bushfor bearine in which the spindle 11 turns while tl e' wire at t heother side of'such breakis V V connectedito the contact 15;

The said mechanism of the cut-out is enclosed in a suitable case 18 from the e;- terior of which projects the knob 10.

The ironis provided with thermostatic means arranged within the thermal influence of the"heating'element, such thermostatic meansconsistingpreferably of a bimetallic s'trip26 adapted to bend or become "distortedin response to variations of temperature. The sa'id 'strip is provided with 1 t d to control an electric contact 19 arranged tdco-operate with'a stationary 20, the arrangement being such that while the temperature of'the iron remains of the heating "element,

below a predetermined degree the saidconta'cts will lie apart, but .upon .theiteniper'ature exceedin a 'Jredetermined de ree the contact 19 will make electrical connection with the contact 20. This thermostatic C0111 trol of the contacts is similar to certain 7 circuit objectionable, one of such contacts may be connected with its corresponding terminal through a suitable resistance as 22 which will be less than that of the resistance r This 7 arrangement necessitates no structural'alteration to the iron beyond the addltion thereto ot' thethermo stat With its contacts and resistance 22 and the necessary connections to theterminals-21 and 23 and consequently the ordinary two-wire cord 24; and its plug 25 will 'serve for connecting the iron to the circuit.

The cut-out will preferably be mounted upon a wall or other fixed point and the customary wall plug 27 may be employed to connect the flexible cord 2e with the circuit. The usual switch 28 may also be employed in the circuit for the purpose of switching the current onand off as customary. V

in operation thecurrentbeingswitched' on and the switch of the cutout having been closed by manipulation of the knob 10 7 so toplace the cut out inthe condition shownlin full lines Flg. 2 the current from the circuit 2 cwill-fiowthrougli the element:

pthus heating theiiron in the usual custonr' ary manner. The current will 10f course flow through thewinding 6 but will not energize the latter sufficiently to raise the core '4 while such winding'beingof low resistance will have practically no effect upon the'flow of current to the elem nt." Upon the temperature of the iron rising above apredetermined degree however the 1 thermostat will causethe contacts 19 and 20' to establish electrical connection with the result thatthe element3 will be short-' circuited either directly or through the lower resistance'22 as the case maybe;'thereby permitting an increased current'to 'flow through the coil 6 which will in consequence raise the core 7 andsfo open the switch 4."

' V The'switch 4: may be again 'clo'sed'by manipulation of the knob l0jbut if this'is ef- V fected before the temperature of the iron has fallen to an allowable degree the cutout will again operate and open the circuit upon the arm 13 resuming its connection with the contact 15.

From the foregoing description therefore it will be understood that the present invention not only serves to open the circuit upon the temperature of the iron rising above apredetermined degree but also renders it impossible for any one to maintain the circuit closed until the temperature of the iron has fallen below such predetermined limit.

I claim:

1. In a device of the class described, the combination of an electric circuit, a switch in said circuit, a heating element and an electromagnet connected in series in said circuit, said magnet being adapted when energized to operate said switch thereby to open the circuit. a thermostatic device disposed adjacent to said heating element and adapted to short circuit the same and increase the current through said electromagnet thereby to energize the same, said switch being adapted to remain open after the magnet is deenergized, and manually operated means for operating the switch thereby to close the circuit.

2. In a device of the class described, the combination of an electric circuit. a switch in said circuit, a heating element and an electromagnet connected in series in said circuit. said magnet being adapted when energized to operate said switch thereby to open the circuit, a thermostatic device disposed adjacent to said heating element and adapted to short circuit the same, a resistance element of lower resistance than said heating element in series with said thermostatic device and electromagnet whereby when the heating element is short circuited the current through said electromagnet is increased thereby to energize the same, and

manually operated means for operating the switch thereby to close the circuit.

3. In a device of the class described, the combination of an electric circuit, a switch in said circuit, a heating element and an electromagnet connected in series in said circuit, said magnet being adapted when energized to operate said switch thereby to open the circuit, a thermostatic device disposed adjacent to said heating element and adapted to short circuit the same and increase the current through said electromagnet thereby to energize the same, a second switch in said circuit. and manually operated means for closing the first switch, said manually operated means being adapted to open said second switch when moved into position to close the first switch.

4:. In a device of the class described, the combination of an electric circuit, a switch in said circuit, a heating element and an electromagnet connected in series in said circuit, said magnet being adapted when energized to operate said switch thereby to open the circuit, a thermostatic device disposed adjacent to said heating element and adapted to short circuit the same and to increase the current through said electromagnet .thereby to energize the same, manually operable means for closing said switch, a second switch in said circuit and having a movable member, and means connecting said movable member with said manually operable means, said connecting means being adapted to normally retain said second switch closed and to open the same when the manually operable means is moved into position to close the first switch.

In testimony whereof I afiiX my signature in presence of two witnesses.

CHARLES ADAMS SIMPSON. lVitnesses CYRIL CARLYN GOATES,

SIDNEY JAMES TRELEAVEN. 

